1. Technical Field of the Invention
The invention concerns a method of establishing a connection, an exchange of a communications network, a service computer for one or more communications networks, and a communications network.
2. Description of Related Art
Strategies for establishing connections under overload conditions of a communications network are known above all from the field of private communications.
The invention starts with a conventional generic method of establishing a connection, such as is used in private branch exchange networks, for example in company networks which have several network accesses to a public telephone network. This method is described for example in the article "Cross-linked TX installations without boundaries" by Hilmar Dehlen, ntz, Volume 45 (1992) on pages 714 to 720 of Brochure 9.
The private communications network is formed of several private branch exchange switching units which are intermeshed by groups of transverse line. Each individual private branch exchange switching unit has access to the public telephone network. If a private branch exchange switching unit receives a call request for a connection to a terminal of another private branch exchange switching unit in the private network, and if a bottleneck in the private network delays the establishment of the requested connection via the private network, an automatic overflow into the public telephone network takes place, i.e. the private branch exchange switching unit reroutes the call request to the public telephone network, thereby establishing a connection to the requested terminal via the public telephone network.
This method of establishing a connection has the disadvantage that considerable costs are incurred by using the public telephone network in the case of an overload, and that there is no possibility of achieving a more uniform utilization of the private communications network.